Villamayor Stone (Golden Stone) As a Global Heritage Stone Resource from Salamanca (NW of Spain)

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Villamayor Stone (Golden Stone) as a Global Heritage Stone Resource from Salamanca (NW of Spain)

J. GARCIA-TALEGO´ N1*, A. C. IN˜ IGO2, G. ALONSO-GAVILA´ N1 & S. VICENTE-TAVERA3 1Department of Geology, University of Salamanca, Plaza La Merced s/n, 37008 Salamanca, Spain 2IRNASA, Spanish National Research Council, Cordel de Merinas s/n, 37008, Salamanca, Spain 3Department of Statistical, University of Salamanca, Spain *Corresponding author (e-mail: [email protected])

Abstract: Villamayor Stone (VS) is an arkosic stone and is known by several names: (i) VS because the quarries are located in Villamayor de Armunã village (Salamanca, Spain); (ii) Golden Stone due to its patina, which gives the stone a ochreous/golden colour; (iii) Franca Stone is known locally and in historical documents. VS has several varieties ranging from channel to floodplain facies. In this work, we have selected three varieties. VS was quarried and used in the construction of Romanesque monuments such as the Old Cathedral, Gothic monuments including the New Cathedral and the University façade, and Baroque monuments, notably the Main Square. Also, VS was used in the reconstruction of the Roman Bridge (Salamanca, Spain). Currently, VS is quarried by a small number of family businesses, using traditional methods for cladding façades of new buildings. Unfortunately, part of the construction sector went bankrupt in the 2008 crisis. However, VS is still the main stone used in the city of Salamanca for the restoration of monuments, even though used in relatively small quantities in comparison with usage before the economic crisis. It is thus of great importance for future generations that their quarries and the craft of masonry be protected. This work proposes that VS should be designated as a Global Heritage Stone Resource.

The particular charm of a city is a product of the stone to determine its quality and validity as Dimen- geological environment in which it is located. In sion stone indicate this stone would be rated as being the case of Salamanca, Spain (Fig. 1a–e), which of poor quality, and therefore its use should be was declared a World Heritage City by UNESCO discouraged for use in the facades of new buildings in 1988, the singular beauty of the city is provided (Fig. 1a–e). by the Golden Stone (Franca Stone) which is exten- The growing urban sprawl of Salamanca city, as sively used throughout the city center. Quarries in well as the creation of leisure and recreation areas, the district of Villamayor de la Armunã (located have created strong urban pressures around and some 5 kilometres from the city) are the source of within the municipality of Villamayor de la Armunã this stone. (Salamanca). These pressures have impeded the In Salamanca, the construction of the principal development of new quarries, as well as concealing religious and civil monuments maintains a fixed or destroying older quarries, as is currently happen- pattern in the use and position of the stone that is ing in the periphery of La Moral (Villamayor de la used. In the lower parts of monuments and columns Armunã, Salamanca). (base, shaft and capital) other types of Heritage Furthermore, the location itself for new quar- Stones have been used (Fig. 2a–f) such as silici- ries is highly conditioned by the dynamics, dis- fied conglomerates (Sandstone Salamanca For- persion, sediment accumulation, and trajectory of mation (Tosca Stone)), monzogranite (Granite of the river system that generated Villamayor sand- Los Santos) and leucogranite with tourmaline from stone (Alonso-Gavilań et al. 2006). Martinamor (Stone of Vaugnerite, Pajarilla Stone) Villamayor Stone is an arkosic stone of Middle (Molina Ballesteros et al. 1997; Lo´pez-Plaza et al. Eocene age and belongs to the Cabrerizos Sandstone 2007a, b, 2009; Nespereira et al. 2010). Formation (Fig. 2a, b) that comprises braided flu- Tourists are often surprised by the excellent vial systems and palaeosoils at the top of each stra- state of conservation of historic buildings of the tigraphic sequence. The sandstone is known by city of Salamanca. Even so, the results of standar- several names: (i) It is known locally and in histori- dized petrophysical classification of Villamayor cal documents as Franca Stone; (ii) Villamayor

From:Pereira, D., Marker, B. R., Kramar, S., Cooper,B.J.&Schouenborg, B. E. (eds) 2015. Global Heritage Stone: Towards International Recognition of Building and Ornamental Stones. Geological Society, London, Special Publications, 407, 109–120. First published online November 27, 2014, http://dx.doi.org/10.1144/SP407.19 # The Geological Society of London 2015. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics Downloaded from http://sp.lyellcollection.org/ at Books Editorial Committee on April 30, 2017

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Fig. 1. (a) Golden Stone: New Cathedral (Gothic style). (b) West façade and atrium of Saint Esteban Church (15th century): (1) Villamayor Stone; (2) Leucogranite Tourmaline Martinamor; (3) Vaugnerite Stone; (4) Silicified Conglomerate (with CT opal). (c) Main Square built in Golden Stone (17th century). (d) Roman Bridge built with Granite. (e) Golden Stone: a detail of the façade of University of Salamanca (16th century). Downloaded from http://sp.lyellcollection.org/ at Books Editorial Committee on April 30, 2017

VILLAMAYOR STONE FROM SALAMANCA, SPAIN 111

Stone because the quarries are located in Villamayor and the natural patina does not develop. Today de Armunã; (iii) the Golden Stone due to its patina this process is being facilitated by the chloride that produces a ochreous/golden colour on the salts that are used to prevent ice sheets developing façades of monuments of Salamanca (World Heri- on frosty days. tage City, UNESCO 1988), which are built with Furthermore, the façades of the monuments dem- this natural stone. In this paper, Villamayor Stone onstrate a surprising uniformity in which it can be (Golden Stone) is presented as a candidate to be observed that the ashlars have different intrinsic designated a Global Heritage Stone Resource. characteristics, given the wide variety of types of In previous works Villamayor Stone has been Villamayor Stone. This fact suggests that the uni- characterized as it appears in the quarry (Vicente formity of the colour of the surfaces is due to chemi- 1983; Vicente 1984; Vicente & Vicente-Hernańdez cal treatments (artificial patinas) used in order to 1985; Vicente & Brufau 1986; Martıń-Patino et al. achieve a chromatic homogeneity and to protect 1993; Rives & Vicente 1993; Saavedra et al. both the façades of new constructions (20th and 1993; In˜igo et al. 2003). The stones that have under- 21st centuries) and in the restoration of monuments. gone important processes of decay on several repre- These artificial patinas are a mixture of gypsum (a sentative buildings have also been analysed (Rives principal component) and clay soil rich in iron oxy- & Vicente 1993; Madruga et al. 1994; Vicente 1996). hydroxides, feldspars and kaolinite (Sienna type) The high capacity for water absorption, together and some additives (glues, casein, etc) (Rives & with its porous network and mineralogical compo- Vicente 1993). sition, makes Villamayor Stone a stone that is The Villamayor Stone (Fig. 1a–e) was quar- easily workable and sculpted when wet. From this ried for the construction and ornamentation of starting point, real sculptural wonders have been Romanesque religious monuments such as the Old created in the city of Salamanca, a highlight being Cathedral and San Julian church, Gothic monu- the façade of the old University (plateresque style) ments (Spanish plateresque style) such as the New and the entrance to the New Cathedral. Cathedral and the Church of San Esteban, and the Looking at the Villamayor Stone monuments, it sculpted façade of the Salamanca University, one can be deduced that on the façades exposed to the of the oldest Universities in Europe (it was estab- sun and the joint action of wind and rain (Rives lished in 1250); and this stone was used in the gal- & Vicente 1993; Vicente 1996), but without the leries and arcades of the sumptuous Baroque Main constant humidity to produce their arenization, the Square of Salamanca (1729). Villamayor Stone was patina is more intense. Two types of surface modifi- also used in the construction of palaces, walls and in cation of the Villamayor Stone in these monumental the restoration of the Roman Bridge of Salamanca. microenvironments have been defined: (i) on verti- The quarry sites are family owned and thus cal surfaces which have good drainage and are neither the quarrying techniques nor the machinery exposed to the sun, good conservation of the stone employed have changed much over time. The tran- can be observed, and it acquires a beautiful golden sition to democracy in Spain, the adoption of differ- patina and (ii) if the stone is located in zones of ent political models and several economic crises frequent humidity, water with or without salts (nitra- have generated large fluctuations in the labour and tes, chlorides, sulfates, phosphates, etc.), which is consumer markets, and these changes have affected located in the lower parts of the monument, rises the local market. For example, there was a sharp from the bases by capillary action. If the monu- decline in production, which was caused by the ment is located in an area with frequent moisture economic crisis that began in 2008, and up to the (e.g. leaking roofs in poor condition, gargoyles present day there are still few signs of recovery. and spouts blocked by bird excrement), the stone crumbles and the patina effect is not produced. The patina is a symptom of the condition of the stone and Geological setting and quarries of contributes to its conservation (Vicente & Brufau 1986, In˜igo et al. 2003). Villamayor Stone Villamayor Stone was used in the noble and Geological setting upper parts of the walls of existing monuments and buildings because in areas influenced by the capil- The study area is situated within the Iberian Penin- lary rise of water (bases), alteration (decay) is more sula (Fig. 2a), in the southwestern part of the auton- intense and fast due to the presence of smectites in omous community of Castilla y Leoń in sheet 478 of its mineralogical composition, which produces the the Spanish MTN at E/1:50.000, on the right bank swelling and contraction of the same and a lack of of the River Tormes, and it occupies part of the per- mechanical resistance when the material is exposed iphery of the municipalities of Salamanca and Villa- to a high degree of permanent moisture. Therefore, mayor de la Armunã (Fig. 2a). The topography of in these areas the arenization process is very fast this area is characterized by the absence of large Downloaded from http://sp.lyellcollection.org/ at Books Editorial Committee on April 30, 2017

112 J. GARCIA-TALEGO´ N ET AL. Downloaded from http://sp.lyellcollection.org/ at Books Editorial Committee on April 30, 2017

VILLAMAYOR STONE FROM SALAMANCA, SPAIN 113 reliefs and escarpments, the minimum elevation The palaeoenvironmental characteristics which being 768 m (roughly equivalent to the level of the can be deduced from the fossils of turtles and cro- River Tormes) and the maximum being 864 m codiles (Jimeńez 1974) corroborate the idea that (Pizarrales). the changes were not only palaeogeographic but The Duero basin is the largest of all the Cenozoic also palaeoclimatic, changing from a warm sub- basins of the Iberian Peninsula (Alonso-Gavilań tropical climate with distinct seasons (Cretaceous et al. 2004) with an approximate extension of and Upper Palaeogene) to a continental Mediter- about 50 000 Km2. It is a continental basin whose ranean climate (from the beginning of the Eocene origins are to be found at the beginning of the onwards). Cretaceous period, gradually evolving throughout Villamayor Stone occupies a specific position in the Mesozoic and Cenozoic eras (Alonso-Gavilań the general Mesozoic-Cenozoic column at the SW et al. 2012). In general, sedimentation in the Duero edge of the Duero basin (Fig. 2b–f). It forms a basin was conditioned by three factors: tectonics, part of the Cabrerizos Sandstone Formation, consti- climate and the source zone. The interaction of tuting one of four lithofacies that are related later- these three factors and the dimensions of the sedi- ally by changes of facies. Villamayor Sandstone is mentary basin produced differing geodynamic discordant on the (Upper Cretaceous) Salamanca and palaeogeographic features on the edges of the Sandstone Formations (Fig. 2d) which make the zone, and in consequence, the sedimentary process basal deposits of the arkosic Villamayor Sandstone was different in each one of them. This allows very porous and very frangible while the upper three stratigraphic sequences to be distinguished deposits are more silicate rich subarkoses, and meta- and they are separated by discontinuities at basin- morphic minerals are more abundant. Situated scale level (Alonso-Gavilań et al. 2004); the main above them, and inconsistent with them, are red con- area of study being focused on the second sequence, glomerates of Miocene age, which give a reddish Eocene–Oligocene. More specifically, in the west- tinge to the deposits of Villamayor Stone (Fig. 2b). ern and southwestern edges of the Duero basin, the horst and graben tectonics generated conjugate Sedimentary environment geological faults in SW–NE and SE–NW direc- tions. This structure of high and sunken blocks, In this palaeodynamic and palaeogeographic con- generally tilted towards the NW, interacted over text Villamayor Sandstone was generated by a time and conditioned the sedimentation at sub-basin braided river system. This river system was cons- level (Alonso-Gavilań et al. 2004). This process tituted by draining a granitoid and metamorphic produced the location and geographical dispersion source area located in the SW which flowed of Villamayor sandstone. In addition, the lithology towards the NE. The spread of palaeocurrents indi- of the source zone (granitoids and low-grade meta- cates (Alonso-Gavilań et al. 2006) that the braided morphic rocks, greenschist facies from the Pre- flow demonstrated considerable channel mobility, cambrian and Palaeozoic periods) determine the but there was a marked tendency for them to run maturity and composition of the sediments depos- in a northeasterly direction, toward where the river ited whether subarkose or arkose. flowed into the sea. The sediment load, moved by Further, the movement of the Iberian Peninsula saltation and traction, formed large sand deposits, from a latitude of roughly 308Nto408N during the overlapping megaripples, which sometimes consti- Cretaceous, Palaeogene and Neogene periods are tuted authentic sandy plains. reflected in a change in climatic factors, as well as These active channels deposits (facies St, low in the composition of the sediments. The river angle (,108) cross-stratified sand; and Sm, sand, basin became isolated, passing from being close to medium to coarse; Miall 1977), are those which are the sea in the NE during the Palaeogene period to currently exploited as Villamayor Premium Sand- being endorheic and centripetal in the Neogene, stone (Figs 2g, h), and having low clay content are and then open to the west to the Atlantic Ocean, at good aquifers given the high porosity and per- the end of the Cenozoic period, in an open basin. meability (and little or no cementation). In periods

Fig. 2. (a) Geological setting and quarries of Villamayor Stone. (b) General Stratigraphic Section of Salamanca area. (c) Detail of Leucogranite Tourmaline Martinamor (Piedra Pajarilla). (d) Silicified Conglomerate (Salamanca Fm.; Piedra Tosca) core. (e) Villamayor Stone blocks in the quarry. (f) Correlation between Natural Stone and its use in different parts of the architectural structure of the south façade of the New Cathedral of Salamanca. (g) The quarry sites of Villamayor Stone. (h) Location of Villamayor stone varieties used in this study (VAC, Villamayor carbonated; VF, Villamayor fine; VR, Villamayor network) and their correspondence to the sedimentary facies (St, low angle (,108) cross-stratified sand; Sm, sand, medium to coarse; Fm, massive deposits silt or fine grained deposits; and P, pedogenic carbonate). Downloaded from http://sp.lyellcollection.org/ at Books Editorial Committee on April 30, 2017

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Fig. 3. Photomicrographs PPL and XPL of the varieties of Villamayor Stone. (a) Variety of Villamayor Stone (VF) contains 2:1 phyllosilicates and is ﬁne-grained sandstone (objective: x4). (b) Variety of Villamayor Stone (VR) with oxihydroxides of iron, 2:1 phyllosilicates and is medium grained sandstone (objective: x10). (c) Variety of Villamayor Stone (VAC) with the presence of dolomite crystals as cement, or as nodules (objective: x20). (d) Natural Downloaded from http://sp.lyellcollection.org/ at Books Editorial Committee on April 30, 2017

VILLAMAYOR STONE FROM SALAMANCA, SPAIN 115 of flooding, the floodplains grow vertically or fill up size (,100 mm), ocher tones, and is very compact neglected channels. In periods of drought, aban- with abundant clay matrix (Fig. 3a). The VR has doned channels fill up, palaeosoils (Figs 2g, h) fine–medium grain size (.100 mm), reddish tones and carbonation processes are initiated (Fm, silt (Fig. 3b), no cement, low clay matrix and has iron deposits massive or fine grained deposits; and P, oxides present. The VAC has very fine grain size pedogenic carbonate; Miall, 1977). The imperfec- (,100 mm) with nodules of dolomite and clay con- tions produced are known in the quarries by the centrations (Fig. 3c), is white with brown patches, generic name of codones. cemented by carbonate (crystals of dolomite) and Quarry Villamayor Sandstone. The Villamayor abundant clay matrix. quarries are located in the village of Villamayor The main components for all three varieties are de la Armunã, a few kilometres from the city of quartz (up to 60%), feldspar, 2:1 layered silicates Salamanca (Fig. 2a, b, e, g, h), and are considered (smectites), palygorskite-type fibrous silicates, and the type locality of the Villamayor Stone lithofacies small amounts of micaceous minerals (illite/mica) (Alonso-Gavilań et al. 2004). Localizing a Villa- (Fig. 3a–c). Scanning electron microscopy reveals mayor Stone extraction bank to be quarried was fibers of palygorskite lining pores and grains of never an easy task, and in the beginning the choice quartz and feldspar (Fig. 4). The clay minerals, both was based on the quarryman’s own experience. Dig- inherited (illite/mica), as well as those formed ging would begin in the red conglomerate, which is by diagenetic processes (palygorskites, smectites), the top layer of stratigraphic succession (Fig. 2g), embedded skeletal grains (quartz and feldspar) in and if underneath it traces of Villamayor Sandstone whole or in part which may give rise to a porous were found then digging would begin with the network (Fig. 3a–c and Fig. 4). removal of overburden and the rubble was used to Chemical analysis of its major elements shows fill in cavities or former quarries. This activity is that the percentage of SiO2 is high, followed by still practiced today. Al2O3,K2O, Fe2O3, as well as H2O. In the case of The excavation would continue through the for- the reddish coloured samples, a greater quantity of mer floodplain deposits until it encountered a good iron can be observed, due to the presence of iron quality seam of Villamayor Stone. The geometry oxyhydroxides, which gives the material its super- of the former channels would determine the face ficial reddish-brown colour. to be exploited, and the thickness of the seam and the quality of the stone would determine the length of the working life of the quarry (Fig. 2g, h). The Physical characterization: hydric properties potential of the quarry face (base level of extraction) and Hg injection is now determined by the low elevation of the ridges, proximity to the River Tormes, and the por- Regarding the determination of hydric properties osity of Villamayor Stone, which can lead to flood- (In˜igo et al. 1994), the stone can be observed to be ing of the quarry. The quarry location is determined highly porous (.30%) and capable of absorbing by the direction of the braided river system that was large quantities of water by capillarity (Table 1). the origin of the Cabrerizos Sandstone Formation It can be concluded from the values obtained by (Alonso-Gavilań et al. 2006). Hg injection (Table 2) that there are varieties of Vil- lamayor Stone that are microporous (VAC and VF) and other varieties that are macroporous (VR). Intrinsic properties of Villamayor Stone Mineralogical and chemical characterization Colour Its mineralogical composition is determined by The quarry stones come in a variety of colours rang- X-ray diffraction, polarized light optical microscope ing from white to ocher to red, and with exposure and scanning electron microscope. In this paper, to the environment, the stone acquires a natural three varieties of Villamayor Sandstone have been golden patina, as traces of iron and manganese rise selected: carbonated variety (VAC); fine-grained to the surface of the blocks. This process is facili- variety (VF); red variety with iron oxides (VR). tated by cycles of wetting and drying, which cause The varieties differ in grain size, presence of sec- these trace elements to come to the surface ondary minerals, the type of clays and network (Vicente 1983). It is this process that has led to Vil- porosity (Fig. 3a–c). The VF consists of fine grain lamayor Stone being called Golden Stone.

Fig. 3. (Continued) and Aged variety of VF. (e) Natural and Aged variety of VR. After artiﬁcial ageing by freezing/thawing and thermal schock, arenization and ﬁssuration are observed in the microporous variety (VF) and arenization in the macroporous variety (VR). Downloaded from http://sp.lyellcollection.org/ at Books Editorial Committee on April 30, 2017

116 J. GARCIA-TALEGO´ N ET AL.

Fig. 4. SEM micrograph of the Villamayor Stone showing ﬁbers of palygorskite lining pores and grains of quartz and feldspar. Note the network pore that originates: geometry, size and degree of connection network pore.

The chromaticity coordinates (L*, a*, b*) of the Alterability of Villamayor Stone by colour system are presented in Fig. 5. They are used artificial ageing and its conservation to determine colour numerically with a MINOLTA colourimeter (Chroma Metra) (Garcıá-Talegoń treatments et al. 1998). The L* value refers to lightness (or Alterability by artificial ageing (freezing/ darkness), while a* and b* are the chromaticity thawing and thermal shock) (Fig. 3d, e) coordinates. The a* coordinate range between positive values, identified with red, and negative values, The city of Salamanca is located on the Castillian identified with green. The negative values of the b* plateau at an elevation of 800 m with a semiarid coordinate are associated with blue and the positive continental climate and low atmospheric pollution. ones with yellow. Changes in each of the chromatic The minimum and maximum annual temperatures coordinates for each of the tests correspond to the are 217 8C and 40 8C, respectively, with 60 days difference between the magnitude of a coordinate having subzero temperatures and annual precipi- for the treated (or aged) sample and that of the orig- tation of 420 mm. Given this climate, Villamayor inal sample, thus obtaining parameters DL*, Da* Stone is is vulnerable to damage caused by frost and Db*. The difference in total colour is given by weathering (cryoclastism, gelifraction). Its resist- 2 2 2 1/2 the equation DE*ab ¼[(DL*) + (Da*) + (Db*) ] . ance to damage caused by frost depends upon the Stone blocks (5 cm × 5cm× 5 cm) were cut and level of porosity and pore size distribution (network the values of the coordinates were averaged from pore), which each variety possesses, and this is ulti- measurements on these 5 faces. mately dependent upon the clay in which the grains

Table 1. Hydric properties of Villamayor stone: natural from the quarry

Hydric Total Open Real Apparent Capillary absorption Properties porosity porosity density density coefﬁcient (%) (%) (g/cm3) (g/cm3) (g/cm2s1/2)1023

VAC 30 26 2.65 1.86 85 VF 32 25 2.66 1.80 76 VR 37 26 2.66 1.66 70 Downloaded from http://sp.lyellcollection.org/ at Books Editorial Committee on April 30, 2017

VILLAMAYOR STONE FROM SALAMANCA, SPAIN 117

Table 2. Hg Inyection properties of Villamayor stones: natural and aged

Variedad Total Free Trapped Macroporosity Microporosity Porosity Porosity porosity (.7.5 mm) (,7.5 mm) %% % % %

VAC 15.43 7.87 (51) 7.56 (49) 1.31 (8) 14.12 (92) VAC Aged 10.65 7.77 (73) 2.88 (27) 0.76 (7) 9.89 (93) VF 25.68 10.60 (41) 15.08 (59) 3.57 (14) 22.11 (86) VF Aged 20.11 4.18 (21) 15.93 (79) 1.34 (7) 18.77 (93) VR 25.79 6.00 (23) 19.79 (77) 19.00 (74) 6.79 (26) VR Aged 24.52 20.11 (80) 4.41 (20) 20.40 (83) 4.12 (17)

The numbers in parentheses are values based on 100% of the data and relate to the total value of mercury porosity. are embedded, which serves to hold them together. The cube samples of Villamayor Stone (VAC, Extreme changes in temperature cause differen- VF, VR) described above were aged through tial expansion between mineral grains in build- 25 cycles of freezing/thawing and thermal shock ing stones (sandstones). These expansions generate (220 8C to 100 8C) in a simulation chamber, fol- micro and macro discontinuities, allowing the cir- lowing standard recommendations by Tiano & Pec- culation of fluids (water, dissolved salts, etc). chioni (1990). Hg injection properties and colour When water freezes, it produces a volume increase, characterization before and after artificial ageing generating pores (about 9% of original volume). are shown in Table 2 and Figure 5, respectively. This expansion induces stress concentration and Visually, the Villamayor Stone blocks, after the tensile damage in the pores. When the rock thaws, artificial aging caused by the cycles of freezing/ the water flows through the micropores causing thawing and thermal shock, demonstrate rounding new fractures. The intrinsic properties of the sand- of edges and vertices (Fig. 3d, e), as well as a super- stones (porosity, pore size distribution and mineral ficial loss of grains, which produces a consequent content) have a great influence on deterioration. It deterioration of the smoothness of the stone. The is well known that pores in this diameter range types that are most affected have been the micro- (microporosity ,7.5 mm) plays an important role in porous varieties (VF, VAC), which also show signs degradation processes such as haloclasty and geli- of fissures that run through the whole block. The fraction (Camuffo 1996; Garcıá-Talegoń et al. 1999; results of mercury porosimetry of non-aged and aged Ruedrich & Siegesmund 2007; In˜igo et al. 2013). stone blocks measuring the degree of aging caused

Fig. 5. Colour characterization (DE*D.L*Da*Db*) of the three varieties of Villamayor Stone (VAC, VF, VR): non-aged (natural stone from the quarry); Conservation Treatments: RC-70, RC-80; non-aged (before artiﬁcial aging); aged (after artiﬁcial aging by freezing/thawing and thermal shock). Downloaded from http://sp.lyellcollection.org/ at Books Editorial Committee on April 30, 2017

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Table 3. Physical properties in water of Villamayor stones: natural and treated

Sample Apparent Density Total Open Water Absorption Density dap, d, Porosity Pt, Porosity Po, Coefﬁcient 3 (g/cm ) (%) (%) (%) Wac

VAC 1.86 2.65 30 26 85 VAC-RC-70 1.97 2.46 20 4 22 VAC-RC-80 1.99 2.28 13 3 24 VF 1.80 2.66 32 25 76 VF-RC-70 1.94 2.50 22 4 17 VF-RC-80 1.92 2.30 17 3 18 VR 1.66 2.66 37 26 70 VR-RC-70 1.74 2.54 31 3 11 VR-RC-80 1.76 2.46 28 2 9

by freezing/thawing and thermal shock are shown experimental design was implemented: (i) type in Table 2. Values based on 100% of the data relat- of sample; (ii) treatment; (iii) ageing. The analytical ing to the total value of mercury porosity are pre- study was complemented with interaction studies, sented in parentheses in the rest of the parameters. following the Analysis of Variance (ANOVA) Consolidation and water repellent treatments. study, and the corresponding contrasts were per- The Conservation treatments Rhodorsil 70 (RC formed by incorporating a type-1 error-correcting 70) and Rhodorsil 80 (RC80) were from Rhone- factor (Fig. 5). The effect of the consolidation Poulenc and were supplied by Siliconas Hispania. and/or waterproofing treatments and of artificial RC 70 consolidant is a colourless organic sili- ageing on the three varieties of Villamayor Stone cate with a viscosity of 0.86 mPa/s, a density of shows that upon associating the variations in colour 0.890 g/cm3 and a silicone content of 70%. The with DE*, it is seen that artificial ageing alters the solvent is a white spirit. RC80 consolidant and colour of all the natural and treated samples. waterproofer is colourless and a catalyzed organic However, the treatments without ageing do not silicate with a methyl resin in a solution of white modify the colour. Luminosity (DL*) shows signifi- spirit. Its viscosity is 1.13 mPa/s, it has a density cant alterations in all samples. Chromaticity, mea- of 0.905 g/cm3 and a silicone content of 68%. The sured with the Da* coordinate, is modified by application of the products was carried out slightly ageing with colour progressively evolving towards modified NORMAL to the recommendations red, except in VR, which is already reddish. Chro- (Garcıá-Talegoń et al. 1998; In˜igo et al. 2006) by maticity (Db*) is modified by ageing in all varieties immersing the sample into the consolidant fluid and for all treatments. (instead of capillary absorption) and using different concentrations (instead of a single one) in order to facilitate penetration of the product inside the stone Conclusions sample. Treatment was carried out by immersing the samples in white spirit for 30 min, followed Villamayor Stone (or Golden Stone) lends a spe- by immersion in white spirit solutions of the reagents cial aspect to the artistic and historic monuments at three levels of concentration: (i) eight hours of Salamanca, which cannot be compared to any with a 5% solution, (ii) twenty four hours with a other city in the world thanks to the golden patina 40% solution and (iii) forty hours with a 75% which is acquired naturally with the passage of time. solution. The cube samples described above were On the one hand, its physical properties make it an age treated through 25 cycles of freezing/thawing unsuitable material for use in the foundations of his- and thermal shock (220 to 100 8C) in a simulation toric buildings because of important phenomena chamber, following standard recommendations by related to the capillary rising of water. Its strong por- Tiano & Pecchioni (1990). Hydric properties are osity makes it an inappropriate dimension stone in shown in Table 3. The affect of the treatments was certain contexts. However, in sunny zones in which significant for the hydric properties determined for it can quickly dry, this problem is not as bad as all varieties of Villamayor Stone: these treatments mightbeexpected. Arenizationandrougheningtakes produced a decrease of all the values. place in zones where humidity is permanent (micro- Stone blocks (5 cm3) were cut and the values environments where buildings are in the shade, or of the coordinates were averaged from measure- facing north, the lower parts of walls, etc) and where ments on these 5 cm2 faces. A complete three-way the environment contains high levels of water with Downloaded from http://sp.lyellcollection.org/ at Books Editorial Committee on April 30, 2017

VILLAMAYOR STONE FROM SALAMANCA, SPAIN 119 dissolved salts (chlorates, sulphates, nitrates, phos- In˜igo, A. C., Garcia-Talegon, J., Trujillano, R., phates) as, for example in the case of the basements Molina,E.&Rives, V. 2003. Evolution and of buildings where there is a high level of absorp- decay processes in the Villamayor and Zamora sand- Pe´rez-Rodriguez tion of ground water that contains high saline levels. stones. In: , J. L. (ed.) Applied On the other hand, the hydric and Hg injec- Study of Cultural Heritage and Clays. CSIC, Madrid, 47–57. tion properties and mineralogical composition of In˜igo, A. C., Vicente-Tavera,S.&Rives, V. 2006. Stat- this stone render it easy to work when damp, as istical design applied to hydric property behaviour it offers little resistance to being sculpted, as can for monitoring granite consolidation and/or water- be observed in the case of the façade of the Univer- repellent treatments. Materiales de Construccioń, 56, sity of Salamanca. 17–27. The chromatic homogenization of Villamayor In˜igo, A. C., Garcıá-Talegoń, J., Vicente-Tavera, S., Stone is due to its natural golden patina and also Martıń-Gonza´lez, S., Casado-Marıń, S., Vargas- Munõz Pe´rez-Rodrı´guez due to artificial treatments employed for its protec- ,M.& , J. L. 2013. Colour tion and conservation, which reduce the natural and ultrasound propagation speed changes by different ageing of freezing/thawing and cooling/heating in diversity of this beautiful stone. granitic materials. Cold Regions Science and Technol- Villamayor Stone (Golden Stone) is presented as ogy, 85, 71–78. a candidate to be designated a Global Heritage Stone Jimeńez, E. 1974. Iniciacioń al estudio de la paleoclimato- Resource, which can facilitate the preservation of logıá del Paleo´geno de la cuenca del Duero y su posible historical quarries for use in the restoration of monu- relacioń con el resto de la Penıńsula Ibe´rica. Boletıń ments in Salamanca. This name is recorded in an Geolo´gico y Minero de Espanã, 85, 6–12. international designation of geological and heritage Lo´pez-Plaza, M., Gonza´lez-Sańchez,M.&In˜igo, significance. A. C. 2007a. La utilizacioń del leucogranito turmalinı´- fero de Martinamor en los monumentos de Salamanca y Alba de Tormes. Studia Geologica Salmanticensia, 43, 247–257. References Lo´pez-Plaza, M., Gonza´lez-Sańchez,M.et al. 2007b. La utilizacioń de rocas vaugnerı´ticas en los Alonso-Gavilań, G., Armenteros, I., Carballeira, J., monumentos de Salamanca. Studia Geologica Salman- Corrochano, A., Huerta,P.&Rodrı´guez,J.M. ticensia, 43, 115–125. 2004. Cuenca el Duero. In: Vera, J. A. (ed.) Geologıá Lo´pez-Plaza, M., Garcıá De Los Rıós-Cobo, J. I., de Espanã. SGE-IGME, Madrid. 550–556. Lo´pez-Moro, J. J., Gonza´lez-Sańchez, M., In˜igo, Alonso-Gavilań, G., Talegoń, J., Herrero Fernań- A. C., Vicente-Tavera,S.&Jimeńez-Fuentes,E. dez,H.&Herrero, A. 2006. Paleodrenaje del 2009. La utilizacioń del granito de Los Santos en la sistema fluvial de Villamayor: ana´lisis de las paleocor- ciudad de Salamanca. Studia Geologica Salmanticen- rientes y dispersioń de sedimentos (Areniscas de Villa- sia, 45, 7–18. mayor, Eoceno medio, Salamanca). Geo-Temas, 9, Madruga, F., Saavedra,J.&Martıń-Patino,M.T. 17–20. 1994. Eflorescencias y costras sobre areniscas de Villa- Alonso-Gavilań, G., Villalaıń, J. J., Soto, R., mayor. Ensayos de laboratorio. Materiales de Con- Calvo-Rathert, M., Bartolome´, M., Molina- struccioń, 44, 39–44. Ballesteros,E.&Garcıá-Talegoń, J. 2012. Martıń-Patino, M. T., Madruga,F.&Saavedra,J. Aproximacioń a la cronologıá de la Fm. Areniscas de 1993. The internal structure of the Villamayor sand- Salamanca (SO de la Cuenca del Duero) a partir de stone as it affects its use as a construction material. estudios paleomagne´ticos. Geotemas, 13, 1–20. Applied Clay Science, 8, 61–67. Camuffo, D. 1996. Limits of stone sensitivity to freezing– Miall, A. D. 1977. A review of the braided river thawing cycles. In: Vicente, M. A., Delgado Rodri- depositional environment. Earth Science Reviews, 13, gues,J.&Acevedo, J. (eds) Degradation and Conser- 1–62. vation of Granitic Rocksin Monuments. EUROPEA Molina Ballesteros, E., Garcıá Talegoń,J.& COMMISSION, Brussels, Belgium, 455–462. Vicente Hernańdez, M. A. 1997. Palaeoweather- Garcıá-Talegoń, J., Vicente, M. A., Vicente-Tavera, ing profiles developed on Iberian Hercynian Base- S. & Molina, E. 1998. Assessment of chromatic ment and their relationship to the oldest Tertiary changes due to artificial ageing and/or conservation surface in central and western Spain. In: Widowson, treatments of sandstones. Colour Research and Appli- M. (ed.) Paleosurfaces: Recognition, Reconstruction cation, 23, 46–51. and Palaeoenvironmental Interpretation. Geological Garcıá-Talegoń, J., Vicente,M.A.&Molina, E. 1999. Society, London, Special Publications, 120, 175–185. Decay of granite monuments due to salt crystallization Nespereira, J., Blanco, J. A., Yenes,M.&Pereira,D. in a non-polluted urban environment. Materiales de 2010. Opal cementeation in terciary sandstones used Construccioń, 49, 17–27. as ornamental stones. Engineering Geology, 115, In˜igo, A. C., Garcıá-Talegoń, J., Vicente, M. A., 167–174. Vargas, M., Pe´rez-Rodriguez,J.L.&Molina,E. Rives,V.&Vicente, M. A. 1993. Formas de alteraciońde 1994. Granites employed in A´ vila (Spain) II.-Petrophi- la arenisca de Villamayor en distintos microambientes sical characteristics. Materiales de Construccioń, 44, de edificios salmantinos. In: Vicente, M. A., Molina, 28–37. E. & Rives, V. (eds) Alteracioń de granitos y rocas Downloaded from http://sp.lyellcollection.org/ at Books Editorial Committee on April 30, 2017

120 J. GARCIA-TALEGO´ N ET AL.

afines, empleados como materiales de construccioń. In: Arribas Moreno, A., Polo Dıéz,V.&Jimeńez CSIC, Madrid, 75–82. Fuentes, E. (eds) Estudio sobre las alteraciones y tra- Ruedrich,J.&Siegesmund, S. 2007. Salt and ice crystal- tamiento de la Piedra de Villamayor. Caja de Ahorros lisation in porous sandstones. Enviromental Geology, y Monte de Piedad de Salamanca, Salamanca, 52, 225–249. 421–475. Saavedra, J., Madruga,F.&Martıń-Patino,M.T. Vicente, M. A. 1996. Summary of Project STEP-CT- 1993. Clasificacioń de la arenisca de Villamayor 90-0101, granitic materials and historical monu- (Salamanca) por sus caracterı´sticas tecnolo´gicas y ments: study of the factors and mechanisms of estructura interna. Boletıń Geolo´gico y Minero, 104, weathering and application to historical heritage con- 55–63. servation. In: Vicente, M. A., Delgado Rodrigues, Tiano,P.&Pecchioni, E. 1990. Invecchiamento J. & Acevedo, J. (eds) Degradation and Conservation artificiale di materiali lapidei. In: Piacenti, F. (ed.) of Granitic Rocks in Monuments. European Commis- Camera climatiche od ambientali nella ricerca appli- sion, Brussels, 4–44. cata. Centro Stampa Toscana Nuova, Firenze, 37–42. Vicente,M.A.&Brufau, A. 1986. Weathering of Vicente, M. A. 1983. Clay mineralology as the key factor the Villamayor arkosic sandstone used in buildings, in weathering of ‘Arenisca Dorada’ (Golden Sand- under a continental semi-arid climate. Applied Clay stone) of Salamanca, Spain. Clay Mineralogy, 18, Science, 1–3, 265–272. 215–217. Vicente,M.A.&Vicente-Hernańdez, J. 1985. The Vicente, M. A. 1984. Contribucioń al estudio de origin of paligorskite in Villamayor sandstone, Sala- alteracioń de la Piedra de Villamayor en Edificios manca, Spain. Mineralogy and Petrography Acta, Salmantinos y de los posibles me´todos de correccioń. 29, 197–203.